"We need inspiration," declares Morgan Freeman as Nelson Mandela in the midst of Clint Eastwood's ceremonial tale of the 1995 rugby World Cup in post-apartheid South Africa. Mandela is ostensibly talking about the country as a whole, though he may as well be exhorting Invictus itself – a monolithic sporting saga that seems content to pose on the podium, lulled by the belief that its subject matter provides inspiration enough. At times it feels as though Eastwood has elected to skip the contest and proceed straight to the trophy presentation.

It's not that Mandela's turbulent first year as South Africa's president is lacking in drama. Invictus, which has its UK premiere tonight, plays out in a land scarred by apartheid and facing an uncertain future, led by an man still regarded by large swaths of the population as an unrepentant terrorist hell-bent on settling old scores. The genius of Mandela was in somehow managing to soothe these tensions, cajoling his countrymen towards an uneasy truce. But in charting this struggle, Eastwood sticks too close to the playbook and frames history as an airbrushed Hollywood heartwarmer. The implication is that, by the time our hero takes his seat at the world cup finals, none of these issues was ever a problem again.

Casting about for a symbol of the new, integrated South Africa, the newly elected president hits upon what initially seems an unruly and divisive candidate. The Springboks rugby team are not just languishing in the doldrums, they are also seen as a bastion of old white rule and therefore despised by the black majority who cheer whatever team is playing them. But Mandela spies an opportunity. He celebrates the Springboks' lone black player and sets out to woo its foursquare captain, François Pienaar (Matt Damon).

Raised in a family of racist Afrikaans, Pienaar goes to his first meeting like a man contemplating root canal surgery. Needless to say, he comes out converted. "He's the greatest man I've ever met," Pienaar gushes to his wife.

The rest of Invictus (which takes its name from the WE Henley poem) follows the Springboks' unlikely push towards the World Cup final, where they face-off against New Zealand. After a lifetime playing Cinderella, Pienaar's stoic maid is duly invited to the ball. Outside the stadium, a pair of white cops listen to the match on the radio while a black urchin eavesdrops a short distance away. But by the time the contest has reached its conclusion, the cops have hoisted the kid on their shoulders and are presumably planning to pay his way through college. Invictus is that kind of movie.

Decent acting keeps it halfway honest. While hardly a dead-ringer for Mandela, Freeman turns in a diligent, nuanced impersonation that at least hints at the private man behind the public image. His Mandela is by turns wise and wily; his seraphic smile concealing a life of shadows. Meanwhile, Damon makes a good fist of his role as Pienaar, although his character is seldom allowed to be more than a plot device: the Afrikaner who sees the light.

The trouble with Invictus is that it is more monument than motion picture: handsome, reverent and heavy. How curious that this cautious, constrained affair was recently handed the Freedom of Expression award by the National Board of Review. Freedom of expression? Really? Judged in terms of creativity, spectacle and drama, Invictus might as well be stuck on Robben Island.